The electron microprobe analysis of agglutinating foraminifera; results from a Rotaliammina test from the S.W. Pacific

Abstract. Electron microprobe analyses and element distribution images of a Rotaliammina test from Funafuti, S. W. Pacific, are presented. Detailed analysis of both spiral and umbilical surfaces shows that the earliest chambers are richest in organic components, and that the brown coloration of the test correlates with amount of organic material (“tectin”) rather than with iron content. The peripheral flange is shown to be similar in composition to the agglutinant-rich spiral surface of the last chamber. The example serves to illustrate a useful analytical method which has application to the study of the structure and composition of the wall of agglutinating foraminifera in general.